Field of the Invention
The present invention relates to an antenna, especially to a surface-mount multi-band antenna adapted for circuit board with ground metal plane.
Description of Prior Art
As the progress of wireless communication technology, portable electronic products such as laptop computer, smart phone or PDA are developed toward lightweight and compact size. Therefore, the antenna for emitting and receiving electromagnetic wave is needed to size down or change its structure to fit into the compact portable electronic products.
The commercially available multi-band antennas generally adopt Planar Inverted-F Antenna (PIFA) structure. This kind of antenna has simple 2D design and uses PCB technology to directly print copper on PCB to form planar shape multi-band antennas. Alternatively, 3D multi-band antennas can also be formed by pressing metal membrane.
The PIFA structure changes the 2D patterns or geometric shape of metal membrane to achieve multi-band signal transmission and reception. However, the PIFA structure still requires a specific size to have satisfactory signal quality and prevent from out of tuning caused by environment, and the portable electronic product needs a corresponding inner space to accommodate the PIFA structure. It is hard to achieve compact requirement.